1. Field of the Invention
This invention relates to a continuous process for the alkylation of hydrocarbons over a solid acid catalyst, and more in particular a process in which the catalyst is also regenerated.
2. Prior Art
Within the framework of the present invention, the term alkylation refers to the reaction of an alkylatable compound, such as an aromatic or a saturated hydrocarbon, with an alkylation agent, such as an olefin. Without limiting its scope, we will further illustrate the invention by discussing the alkylation of saturated hydrocarbons, in general branched saturated hydrocarbons, with an olefin to give highly branched saturated hydrocarbons with a higher molecular weight.
U.S. Pat. No. 5,523,503 discloses the alkylation of hydrocarbons, i.e. isobutane, in an apparatus comprising at least three reactors. The reactors cycle between a zone in which alkylation is performed and a zone where the catalyst is regenerated. Cycling of the reactors between the two zones occurs by periodically advancing the locations at which the first feed stream and the regenerant stream enter the process in a manner such as to simulate the cocurrent movement of the beds of catalysts relative to the direction of the liquid phase reactant flow.
In this process, the points of feed and regenerant injection move along the reactors. Such a process requires a lot of valves and tubing. A second disadvantage of this process is the need for the introduction into the apparatus of two separate isobutane-containing streams: a feed stream and a regenerant stream. A third disadvantage is that before cycling a reactor from the regeneration to the alkylation zone and vice versa, the reactor needs to be flushed.